Dolomite separation method based on carbonate sediment in modern shallow sea environment

Abstract

The invention relates to the field of mineral separation, in particular to a dolomite separation method based on carbonate deposits in a modern shallow sea environment, which comprises the following steps: pretreating a sample, treating the pretreated sample by using a prepared EDTA-2Na solution, maintaining the pH value at 6.30 in the treatment process, and after the treatment is completed, separating the sample from the sample by using an alkaline solution; injecting deionized water into the reaction container, and drying to complete the separation of the dolomite; according to the scheme, the EDTA-2Na solution is used for thoroughly removing low-magnesium calcite, high-magnesium calcite and aragonite in carbonate sediments in the modern shallow sea environment, only dolomite in carbonate minerals is reserved, the purpose of purifying dolomite from a mixed sample is achieved, and the method is convenient and rapid.

Description

Technical Field

[0001] The invention relates to the field of mineral separation, and in particular to a dolomite separation method based on carbonate sediments in a modern shallow sea environment. Background Art

[0002] Dolomite is widely developed in deep marine carbonate rocks and is also in a supersaturated state in modern seawater, but dolomite precipitation has rarely occurred in the ocean since the Holocene. In addition, it is difficult to precipitate dolomite experimentally under inorganic conditions at room temperature. Most of the calcite and dolomite preserved in ancient strata are low-magnesium calcite and dolomite, and it is difficult to observe metastable aragonite and high-magnesium calcite. In modern shallow sea environments, carbonate sediments are mainly composed of aragonite, low-magnesium calcite, high-magnesium calcite and a small amount of dolomite. It is a natural laboratory for studying carbonate mineral precipitation and mineral phase transformation processes and mechanisms. How to effectively separate dolomite from carbonate sediments in modern shallow sea environments is a technical problem that needs to be solved urgently.

[0003] In view of this, this application is hereby filed. Summary of the invention

[0004] In view of the above problems, an embodiment of the present invention provides a dolomite separation method based on carbonate sediments in a modern shallow sea environment, which uses EDTA-2Na solution to completely remove low-magnesium calcite, high-magnesium calcite and aragonite in carbonate sediments in a modern shallow sea environment, and only retains dolomite in carbonate minerals, thereby achieving the purpose of purifying dolomite from a mixed sample, which is convenient and quick.

[0005] The present invention is achieved through the following technical solutions:

[0006] The embodiment of the present invention provides a dolomite separation method based on carbonate sediments in a modern shallow sea environment, comprising the following steps:

[0007] S1: Pretreatment: pretreat the sample to be separated;

[0008] S2: Treatment solution preparation: prepare EDTA-2Na solution and adjust the pH value to ensure that the pH value of the EDTA-2Na solution is 6.30;

[0009] S3: separation treatment: the pretreated sample is treated with EDTA-2Na solution, and the pH value in the reaction container is kept at 6.30 during the treatment process;

[0010] S4: Post-treatment: After the reaction is completed, deionized water is injected into the reaction container and dried to complete the separation of dolomite.

[0011] In this scheme, a dolomite separation method based on carbonate sediments in a modern shallow sea environment is provided. The method first pre-treats the sample, and then treats the pre-treated sample with a prepared EDTA-2Na solution. During the treatment process, the pH value is maintained at 6.30. After the treatment is completed, deionized water is injected into the reaction container and dried to complete the separation of the dolomite. This scheme uses EDTA-2Na solution to completely remove low-magnesium calcite, high-magnesium calcite and aragonite in carbonate sediments in a modern shallow sea environment, and only retains dolomite in carbonate minerals, thereby achieving the purpose of purifying dolomite from a mixed sample, which is convenient and quick.

[0012] Furthermore, the preprocessing in step S1 includes the following steps:

[0013] S11: crushing treatment, crushing the sample to be processed into 200 mesh;

[0014] S12: Perform XRD test on the crushed samples to obtain the mineral composition and content of the initial samples.

[0015] Furthermore, in step S2, the solubility of the EDTA-2Na solution is 0.27 mol / L.

[0016] Furthermore, in step S2, the preparation of the treatment solution includes the following steps:

[0017] S21: weigh 100.44 g of Na2EDTA·2H2O reagent, add deionized water to 1 L, heat to 25°C and stir to form an initial solution;

[0018] S22: Divide the initial solution into two parts, one of which is a regulating solution and the other is a treating solution, wherein the pH value of the treating solution is adjusted to 6.30 using a 500 g / L NaOH solution.

[0019] Furthermore, in step S3, the sample processing includes the following steps:

[0020] S31: Determine the content of other carbonate minerals in the sample except dolomite based on XRD test;

[0021] S32: adding the sample to react according to the molar ratio of the treatment liquid to other carbonate minerals of 1:1;

[0022] S33: During the reaction, the pH value is adjusted using the regulating solution to ensure that the pH value is maintained at 6.30 during the reaction.

[0023] Furthermore, in step S3, the reaction temperature is 25°C.

[0024] Furthermore, in step S3, the reaction time is 15 to 20 minutes.

[0025] Furthermore, in step S3, the drying temperature is 40°C.

[0026] Furthermore, the method further includes a S5 verification step of performing XRD test and analysis on the post-processing product.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The embodiment of the present invention provides a dolomite separation method based on carbonate sediments in a modern shallow sea environment. The method first pre-treats a sample, and then treats the pre-treated sample with a prepared EDTA-2Na solution. During the treatment process, the pH value is maintained at 6.30. After the treatment is completed, deionized water is injected into a reaction container and dried to complete the separation of dolomite. The scheme uses EDTA-2Na solution to completely remove low-magnesium calcite, high-magnesium calcite and aragonite in carbonate sediments in a modern shallow sea environment, and only retains dolomite in carbonate minerals, thereby achieving the purpose of purifying dolomite from a mixed sample, which is convenient and quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative work:

[0030] Figure 1 A flow chart of a separation method provided by an embodiment of the present invention;

[0031] Figure 2 Provide an XRD pattern before separation for an embodiment of the present invention;

[0032] Figure 3 The XRD pattern after separation is provided for the embodiment of the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessary to implement the present invention.

[0035] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Example

[0037] like Figure 1 As shown, the embodiment of the present invention provides a dolomite separation method based on carbonate sediments in a modern shallow sea environment, comprising the following steps:

[0038] S1: Pretreatment: pretreat the sample to be separated;

[0039] S2: Treatment solution preparation: prepare EDTA-2Na solution and adjust the pH value to ensure that the pH value of the EDTA-2Na solution is 6.30;

[0040] S3: separation treatment: the pretreated sample is treated with EDTA-2Na solution, and the pH value in the reaction container is kept at 6.30 during the treatment process;

[0041] S4: Post-treatment: After the reaction is completed, deionized water is injected into the reaction container and dried to complete the separation of dolomite.

[0042] In step S4, after the reaction is completed, deionized water is used to dilute the solution concentration and increase the pH value through post-treatment to ensure that the dolomite is not dissolved subsequently.

[0043] Specifically, the remaining sample after the reaction is dried, and a suction filtration device may be used to filter the remaining sample in advance, thereby improving the drying efficiency.

[0044] As those skilled in the art should know, since a dilute solution of a strong acid will also dissolve carbonate minerals indiscriminately, this solution uses EDTA-2Na solvent for treatment. EDTA-2Na is a chelating agent for metal ions with an ionic charge greater than 2 (>2+). For carbonate minerals, the dissolution order of EDTA is calcite, aragonite, dolomite, and magnesite. According to the dissolution order of carbonate minerals, in a solution with a pH of 6.3, the differentiation effect of calcite, aragonite and dolomite is the greatest. Selecting a low concentration of EDTA solution can prevent the target mineral dolomite from being dissolved due to excessive concentration.

[0045] In this scheme, a dolomite separation method based on carbonate sediments in a modern shallow sea environment is provided. The method first pre-treats the sample, and then treats the pre-treated sample with a prepared EDTA-2Na solution. During the treatment process, the pH value is maintained at 6.30. After the treatment is completed, deionized water is injected into the reaction container and dried to complete the separation of the dolomite. This scheme uses EDTA-2Na solution to completely remove low-magnesium calcite, high-magnesium calcite and aragonite in carbonate sediments in a modern shallow sea environment, and only retains dolomite in carbonate minerals, thereby achieving the purpose of purifying dolomite from a mixed sample, which is convenient and quick.

[0046] In some embodiments, the preprocessing in step S1 includes the following steps:

[0047] S11: crushing treatment, crushing the sample to be processed into 200 mesh;

[0048] S12: Perform XRD test on the crushed samples to obtain the mineral composition and content of the initial samples.

[0049] Specifically, in some embodiments, in order to ensure the crushing effect, a screening step is provided before the sample to be processed is crushed, and the screening step is used to screen out large biological particles in the sample.

[0050] Specifically, the specific method for achieving crushing includes but is not limited to processing with an oscillating crusher or a ball mill.

[0051] In some embodiments, the solubility of the EDTA-2Na solution in step S2 is 0.27 mol / L.

[0052] In some embodiments, the preparation of the treatment solution in step S2 includes the following steps:

[0053] S21: weigh 100.44 g of Na2EDTA·2H2O reagent, add deionized water to 1 L, heat to 25°C and stir to form an initial solution;

[0054] S22: Divide the initial solution into two parts, one of which is a regulating solution and the other is a treating solution, wherein the pH value of the treating solution is adjusted to 6.30 using a 500 g / L NaOH solution.

[0055] Specifically, as those skilled in the art should know, the amount of Na2EDTA·2H2O is 372 g / mol, and 100.44 g can be weighed to prepare an EDTA-2Na solution with a concentration of 0.27 mol / L.

[0056] In some embodiments, the sample processing in step S3 includes the following steps:

[0057] S31: Determine the content of other carbonate minerals in the sample except dolomite based on XRD test;

[0058] S32: adding the sample to react according to the molar ratio of the treatment liquid to other carbonate minerals of 1:1;

[0059] S33: During the reaction, the pH value is adjusted using the regulating solution to ensure that the pH value is maintained at 6.30 during the reaction.

[0060] Specifically, in step S31, based on the XRD test, the content of various minerals in the sample can be determined according to the molar ratio of the solution to other carbonate minerals of 1:1, that is, the molar ratio of the total content of low-magnesium calcite, high-magnesium calcite and aragonite to the solution is 1:1.

[0061] Specifically, in order to ensure that the pH value is maintained at 6.30 during the reaction, it can be detected by a pH meter.

[0062] In some embodiments, in step S3, the reaction temperature is 25°C.

[0063] In some embodiments, in step S3, the reaction time is 15 to 20 minutes.

[0064] In some embodiments, in step S3, the drying temperature is 40°C.

[0065] In some embodiments, an S5 verification step is also included, in which the post-processing product is subjected to XRD testing and analysis.

[0066] Specifically, by performing XRD test analysis on the post-treatment product, the treatment effect can be verified to ensure that low-magnesium calcite, high-magnesium calcite and aragonite are completely removed.

[0067] Specifically, those skilled in the art should know that after completing the separation of dolomite, various sample preparations for subsequent experiments, such as scanning electron microscopy sample preparation, element and isotope geochemical sample preparation, etc., can be completed as required to realize the application of dolomite.

[0068] In a specific embodiment, the modern shallow sea carbonate sediments in Abu Dhabi, Persian Gulf were used as the research object to conduct separation experiments on dolomite and other carbonate minerals.

[0069] (1) Select fresh field outcrops and drill cores for macroscopic and microscopic petrological observations and select appropriate samples.

[0070] The large biological particles in the sample are selected and screened out, and then the screened samples are ground into 200 mesh using an oscillating sample crusher or a ball mill, and XRD tests are performed on them to obtain the initial mineral composition information, such as Figure 2 As shown, the XRD spectrum shows that the minerals of modern shallow marine carbonate sediments in Abu Dhabi are complex, mainly aragonite and calcite, followed by quartz and feldspar, while the dolomite content is very low, among which Q represents quartz, F represents feldspar, H represents halite, A represents aragonite, C represents calcite, and D represents dolomite.

[0071] (2) Prepare EDTA-2Na solution.

[0072] The preparation of 1L 0.27M EDTA-2Na solution specifically includes: weighing 100.44g of the reagent Na2EDTA·2H2O (the amount of substance is 372g / mol), adding deionized water to 1L, and heating to 25°C, stirring to fully dissolve the reagent. Then, the pH of the dissolved 0.27M EDTA-2Na solution is tested using a pH meter, and part of the initial solution is retained for subsequent adjustment of the pH during the reaction; on this basis, the other part of the EDTA-2Na solution is adjusted to a pH value of 6.30 using 500g / L NaOH for use at the beginning of the experiment.

[0073] (3) Dissolution experiments were conducted on selected samples to separate dolomite from other carbonate minerals.

[0074] The prepared pH is 6.30, 0.27M EDTA-2Na solution, according to the solution and other carbonate minerals (low magnesium calcite, high magnesium calcite and aragonite) molar ratio of 1:1 content is added to the powder sample, the temperature of the reaction solution is 25 ° C, after the reaction starts, the initial solution prepared in step (2) (without pH adjustment) is used to adjust the pH of the reaction solution to 6.30, and the reaction is continued for 15 to 20 minutes. After the reaction is completed, the solution concentration is diluted with deionized water and the pH is increased to ensure that the subsequent dolomite is not dissolved, and the remaining sample is filtered using a suction filtration device and dried at 40 ° C.

[0075] (4) Mineral composition analysis of separated samples

[0076] The remaining samples were subjected to XRD test analysis again. The results are as follows Figure 3 As shown, after the separation experiment, the XRD spectrum shows that the remaining sediment only retains quartz, feldspar and dolomite, which significantly improves the purity of dolomite, where Q represents quartz, F represents feldspar, and D represents dolomite.

[0077] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dolomite separation method based on carbonate sediments in a modern shallow sea environment, characterized in that: The steps include: S1: Pretreatment: pretreat the sample to be separated; S2: Treatment solution preparation: prepare EDTA-2Na solution and adjust the pH value to ensure that the pH value of the EDTA-2Na solution is 6.30; S3: separation treatment: the pretreated sample is treated with EDTA-2Na solution, and the pH value in the reaction container is kept at 6.30 during the treatment process; S4: Post-treatment: After the reaction is completed, deionized water is injected into the reaction container and dried to complete the separation of dolomite.

2. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: In step S1, the preprocessing includes the following steps: S11: crushing treatment, crushing the sample to be processed into 200 mesh; S12: Perform XRD test on the crushed samples to obtain the mineral composition and content of the initial samples.

3. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: In step S2, the solubility of the EDTA-2Na solution is 0.27 mol / L.

4. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 2, characterized in that: In step S2, the preparation of the treatment solution includes the following steps: S21: weigh 100.44 g of Na2EDTA·2H2O reagent, add deionized water to 1 L, heat to 25°C and stir to form an initial solution; S22: Divide the initial solution into two parts, one of which is a regulating solution and the other is a treating solution, wherein the pH value of the treating solution is adjusted to 6.30 using a 500 g / L NaOH solution.

5. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 4, characterized in that: In step S3, sample processing includes the following steps: S31: Determine the content of other carbonate minerals in the sample except dolomite based on XRD test; S32: adding the sample to react according to the molar ratio of the treatment liquid to other carbonate minerals of 1:1; S33: During the reaction, the pH value is adjusted using the regulating solution to ensure that the pH value is maintained at 6.30 during the reaction.

6. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: In step S3, the reaction temperature is 25°C.

7. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: In step S3, the reaction time is 15 to 20 minutes.

8. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: In step S3, the drying temperature is 40°C.

9. The dolomite separation method based on carbonate sediments in a modern shallow sea environment according to claim 1, characterized in that: The method further comprises a S5 verification step of performing XRD test and analysis on the post-processed product.

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